When an autonomous mobile device, or a so-called robotic device, is operating in a specific working area, it is usually designed to move following a predefined algorithm. However, if there is an obstacle or a drop in the moving path of the autonomous mobile device, it is more than likely that the autonomous mobile device can be jammed by the obstacle or damaged when falling from the drop, and thus the autonomous mobile device is no longer operational. Therefore, it is essential that any autonomous mobile device must be equipped with certain obstacle/cliff avoiding apparatus.
Conventionally, an autonomous mobile device utilizes two sets of sensors as its obstacle/cliff avoiding apparatus, whereas the two sets of sensors are enabled to function independent to each other, and each can be an infrared sensor, an ultrasonic sensor, or a mechanical bumping sensor. Unfortunately, such conventional autonomous mobile devices usually are complicated and costly.
Please refer to FIG. 1, which is an autonomous cleaning apparatus disclosed in U.S. Pub. No. 20040143930, entitled “Obstacle Sensing System for an Autonomous Cleaning Apparatus”. As seen in FIG. 1, the obstacle sensing system of the autonomous cleaning apparatus is primarily a front bumper part 11, being movably arranged in front of a chassis 10 of the cleaning apparatus, by which, when the front bumper part 11 encounters and obstacle or obstruction, the movement between the chassis 10 and the front bumper part 11 can be sensed and causes a control signal to be transmitted to the guidance system, and then the guidance system can maneuver the cleaning apparatus around the obstacle or obstruction. However, the aforesaid obstacle sensing system can only sense an obstacle when the apparatus applying the same had come into contact with the obstacle directly, such that the aforesaid obstacle sensing system is considered less efficient and can be easily damaged after several collisions.
Please refer to FIG. 2, which is a robot obstacle detection system disclosed in U.S. Pat. No. 6,594,844. The robot obstacle detection system 20 of FIG. 2 employs a plurality of sensors 21, 22 as its primary detection means, whereas each sensor includes an optical emitter which emits a directed beam having a defined field of emission and a photon detector having a defined field of view which intersects the field of emission of the emitter at a region. As seen in FIG. 2, the sensors 21 are arranged in front of the robot 23 for detecting obstacles or walls blocking the moving path of robot 23, and the sensors 22 are arranged at the bottom of the robot 23 for detecting a drop, by which the robot 23 is enabled to maneuver around the obstacle or drops. However, as the angle of detection of each sensors 21, 22 is fixed, it is required to have a plurality of sensors 21, 22 arranged in the robot 23 for widening the detection angle and thus avoiding blind spot. However, as there are more than one sensor 21, 22 required in the robot 23, the robot obstacle detection system 20 is complicated and costly.